Nowadays, the so-called Smart Entry System (registered trademark) is used in door handle devices. In the Smart Entry System, communication is performed between a portable device, which is carried by a vehicle user, and a transceiver of a vehicle so as to, for example, recognize a vehicle user is approaching or leaving the vehicle user and detect a lock command and an unlock command generated by the vehicle user to automatically lock and unlock the vehicle door. Patent Document 1 describes an example of such a conventional door handle device. FIG. 8 shows the front structure of the door handle device described in patent document 1. FIG. 9 shows the cross-sectional structure taken along line 9-9 in FIG. 8.
As shown in FIGS. 8 and 9, the door handle device has a door handle 100 including an outer panel 200 of the vehicle door and a grip 110, which defines an area into which a vehicle user's hand is insertable. The grip 110 includes an unlock sensor SULK, which is for detecting an unlock command generated by the vehicle user. An operation unit, which is for operating an opening/closing mechanism of the vehicle door, extends into the door through the outer panel 200 from one end 120 of the door handle 100. The end 120 includes a lock sensor SLK, which is for detecting a lock command generated by the vehicle user. The lock sensor SLK and the unlock sensor SULK are each a capacitance sensor that detects changes in the capacitance and includes a detection electrode. The sensors SLK and SULK each determine that the lock command or the unlock command has been issued when detecting a change in the capacitance that occurs when the vehicle user's hand approaches the corresponding detection electrode. For instance, when CPANEL represents a reference value for the capacitance between the outer panel 200 of the vehicle door and the detection electrode of the lock sensor SLK, it is determined that the lock command has not been issued if the value of the capacitance detected by the lock sensor SLK does not greatly differ from the reference value CPANEL. When the vehicle user's hand approaches the detection electrode, a new capacitance CT, which is electrically connected in parallel to the capacitance CPANEL, is formed between the detection electrode and the vehicle user's hand (synthesized capacitance CPANEL+CT). Since the value of the synthesized capacitance is greater than the reference value CPANEL by an amount corresponding to the capacitance CT, it is determined that a lock command has been issued. This detection principle is applied in the same manner to the unlock sensor SULK. In the door handle device of patent document 1, the lock sensor SLK and the unlock sensor SULK are arranged at different parts of the door handle 100. The lock command and the unlock command are thus distinguished from each other by the vehicle user touching these different parts of the door handle 100.
As shown in FIG. 8, the door handle device of patent document 1 includes a lock detection electrode (lock sensor SLK) arranged in an area (area facing away from the outer panel 200) of the end of the grip 110 closer to the outer surface. Thus, when the vehicle user inserts his or her hand between the grip 110 and the outer panel 200 to perform an unlock operation and pulls the door handle 100 to open the door, the hand is apt to entering the detection range of the lock sensor SLK. In such a case, accurate detections may be hindered since the detection of the unlock command by the unlock sensor SULK and the detection of the lock command by the lock sensor SLK are simultaneously performed. Further, when the door is open, the vehicle user may perform unintentional operations such as the lock operation if the vehicle user's hand enters the detection range of the lock sensor SLK.
[Patent Document 1] Japanese Patent No. 3502848